WO2006035907A1

WO2006035907A1 - Wave gear device

Info

Publication number: WO2006035907A1
Application number: PCT/JP2005/018028
Authority: WO
Inventors: Jutei Ri
Original assignee: Nabtesco Corporation
Priority date: 2004-09-30
Filing date: 2005-09-29
Publication date: 2006-04-06
Also published as: TW200613662A; US20080060473A1; EP1813836A1; KR20070073756A; CN101031737A; JP2006097861A

Abstract

A wave gear device capable of transmitting a larger torque. The silk hat type wave gear device (10) comprises an annular circular spline (20) on which an internal gear part (21) is formed, a flexible flex spline (30) having an external gear part (31) on which external teeth (31a) partially meshed with the internal gear part (21) are formed and disposed on the inside of the circular spline (20), and a wave generator (40) disposed on the inside of the flex spline (30) and rotated relative to the circular spline (20) while deflecting the flex spline (30). The flex spline (30) comprises a boss part (32) for fixing it to an external member and a connection part (33) connecting the external gear part (31) to the boss part (32). In the connection part (33), its cross sectional shape provided when it is cut in a plane passing the rotating axis (30a) of the flex spline (30) is so formed that its thickness is gradually decreased from the external gear part (31) side and the boss part (32) side to the roughly center side, and two visible outlines (33a, 33b) opposed to each other on the cross sectional shape are formed in roughly circular arc ones.

Description

Specification

Wave gear device

Technical field

The present invention relates to a wave gear device that transmits torque.

Background art

Conventionally, as a wave gear device, one having a flexible external gear having a curved portion in which a diameter gradually decreases from a diaphragm side toward a body side and is curved is known! / (For example, see Patent Document 1)

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-28122 (Page 3-4, Fig. 3)

Disclosure of the invention

Problems to be solved by the invention

However, in the conventional wave gear device, the stress is concentrated on the diaphragm due to the torque transmitted from the internal gear to the external gear, so that the diaphragm is not broken by the stress concentrated on the diaphragm. The problem is that we can't transmit the torque and force.

[0004] An object of the present invention is to provide a wave gear device capable of transmitting a torque larger than the conventional one.

Means for solving the problem

[0005] The wave gear device of the present invention includes an annular internal gear formed with internal teeth and an external tooth portion formed with external teeth partially meshed with the internal teeth. A flexible external gear arranged inside the gear, and a wave generator arranged inside the external gear to rotate the external gear with respect to the internal gear. The external gear has a fixed portion for fixing to an external member, and a connection portion for connecting the external tooth portion and the fixed portion, and the connection portion passes through the rotation shaft of the external gear. The cross-sectional shape when cut in a plane is a shape in which the thickness gradually decreases from the external tooth side and the fixed part side toward the center, and the two opposing outlines on the cross-sectional shape are substantially arcs. It has a certain configuration.

With this configuration, the wave gear device of the present invention is cut along a plane passing through the rotation axis of the external gear. Since the cross-sectional shape of the connecting portion of the external gear at this time is such that the thickness gradually decreases from the external gear portion side and the fixed portion side toward the center, the torque transmitted from the internal gear to the external gear It is possible to suppress the concentration of stress on a part of the external gear than before, and to transmit a larger torque than before.

[0007] In the wave gear device of the present invention, at least a part of one of the two outlines is a first arc, and at least a part of the other of the two outlines is the first outline. An arc is a second arc having a different radius and center position, and the first arc and the second arc have a configuration in which the thinnest portion of the approximate center having the smallest thickness among the cross-sectional shapes is formed. is doing.

Furthermore, in the wave gear device of the present invention, at least a part of one of the two outlines is a first arc, and at least a part of the other of the two outlines is a second arc, The first arc and the second arc are defined by a center position of the first arc and a center position of the second arc which are smaller than a radius of the first arc and a radius of the second arc. A straight line passing therethrough has a configuration that intersects the first arc and the second arc at substantially the center between the external tooth portion side and the fixed portion side in the cross-sectional shape of the connection portion.

[0008] With this configuration, the wave gear device of the present invention has a simple shape at the thinnest portion, so that the processing of the external gear can be facilitated.

The invention's effect

[0009] The present invention can provide a wave gear device capable of transmitting a torque larger than the conventional one.

Brief Description of Drawings

FIG. 1 is a side cross-sectional view of a wave gear device according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged side sectional view of the flex spline shown in FIG.

FIG. 3 is a side sectional view of a wave gear device according to a second embodiment of the present invention.

FIG. 4 is a partially enlarged side sectional view of the flex spline shown in FIG.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0012] (First embodiment) First, the configuration of the wave gear device according to the first embodiment will be described.

As shown in FIG. 1, a top hat wave gear device 10 as a wave gear device according to the present embodiment includes a thick-walled circular plastic gear as an annular internal gear having internal teeth 21 formed therein. Inner 20 and outer teeth 31 formed with outer teeth 31a partially mating with inner teeth 21 and having a thin wall as a flexible external gear disposed inside circular spline 20 A top hat-shaped flex spline 30 and a wave generator 40 that is arranged inside the flex spline 30 and rotates with respect to the circular spline 20 while constricting the flex spline 30 are provided. /!

The flex spline 30 has a boss portion 32 as a fixing portion for fixing to an external member (not shown), and a connection portion 33 that connects the external tooth portion 31 and the boss portion 32.

Further, the wave generator 40 is in force with an elliptical cam 41 and a thin bearing 42 incorporated on the outer periphery of the cam 41.

As shown in FIG. 2, the connecting portion 33 of the flex spline 30 has a cross-sectional shape when cut along a plane passing through the rotating shaft 30a of the flex spline 30 (see FIG. 1). Also, the boss 32 side force has a shape in which the thickness gradually decreases toward the center. In addition, the connecting portion 33 is opposite to the outer toothed portion 31 side of the boss portion 32 with respect to the two opposing outer toothed portion 31 side surfaces 32a on the cross-sectional shape when cut along a plane passing through the rotating shaft 3 Oa. Projected to the side 32b side.

[0017] It should be noted that the outer shape line 33a is formed by an arc 34 as a first arc of a radius R1 and a center position Ol that are continuous with the external tooth portion 31 and the boss portion 32. The outline 33b is formed by the arc R as the second arc at the center R02 and the radius R2 connected to the outer tooth part 31, and the arc R at the center R03 and the arc 36 at the center position 03 connected to the arc 35 and the boss part 32. Has been. Here, the circular arc 34 and the circular arc 35 form the thinnest portion 37 at the approximate center where the thickness is the thinnest among the cross-sectional shapes of the connecting portion 33 when cut along a plane passing through the rotating shaft 30a. That is, the point where the straight line passing through the center position Ol of the first arc and the center position 02 of the second arc intersects the first and second arcs is located at the center of the connecting portion 33, respectively. Also, the radius R1 is smaller than the radius R2, and the distance from the thinnest part 37 to the center position Ol is shorter than the distance from the thinnest part 37 to the center position 02 !.

Next, the operation of the top hat wave gear device 10 will be described. [0019] For example, in the top hat type wave gear device 10, the circular spline 20, the boss part 32 of the flex spline 30 and the cam 41 of the wave generator 40 are fixed to the industrial robot casing, output shaft and input shaft, respectively. In this state, when rotational motion is input from the input shaft to the cam 41 of the wave generator 40, the rotational motion input to the cam 41 of the wave generator 40 is decelerated internally and from the boss portion 32 of the flex spline 30. Output to the output shaft.

The top hat type wave gear device 10 decelerates the rotational motion input to the cam 41 of the wave generator 40 and outputs it from the boss part 32 of the flex spline 30. The force that transmits torque to the spline 30 The cross-sectional shape of the connection part 33 of the flex spline 30 when it is cut along the plane passing through the rotating shaft 30a of the flex spline 30 is the outer tooth part 31 side and the boss part 32 side force at the approximate center. Therefore, it is possible to suppress the concentration of stress on a part of the flex spline 30 due to the torque transmitted from the circular spline 20 to the flex spline 30.

[0021] As described above, the top-hat type wave gear device 10 has conventionally been characterized in that the stress is concentrated on a part of the flex spline 30 due to the torque transmitted from the circular spline 20 to the flex spline 30. Therefore, when the size and weight are the same as in the past, larger torque can be transmitted, and when the size of the torque that can be transmitted is the same as the conventional size and weight. Can be reduced as compared with the prior art.

[0022] Further, in the top hat type wave gear device 10, the thinnest portion 37 is formed by the arc 34 and the arc 35, and the shape of the thinnest portion 37 is simple. Addition can be facilitated. The thinnest portion 37 may have a more complicated shape.

[0023] It should be noted that the top hat-type wave gear device 10 has a force in which the outline 33a is a complete arc. If the outlines 33a and 33b are substantially arcs as a whole, at least one of the outline 33a and the outline 33b is It does not have to be a complete arc. For example, the top hat type wave gear device 10 may have a straight line portion at least at a part of the outlines 33a and 33b as long as the outlines 33a and 33b are substantially arcs as a whole. [0024] (Second Embodiment)

First, the configuration of the wave gear device according to the second embodiment will be described.

Of the configuration of the wave gear device according to the present embodiment, the same configuration as the configuration of the silk hat type wave gear device 10 (see FIG. 1) according to the first embodiment is described with reference to silk The same reference numerals as in the configuration of the hat-type wave gear device 10 are attached, and detailed description thereof is omitted.

As shown in FIG. 3, the cup-type wave gear device 60 as the wave gear device according to the present embodiment includes an external tooth in which an external tooth 81 a partially meshed with the internal tooth 21 is formed. Instead of the flex spline 30 (see Fig. 1), the top hat is replaced with a thin cup-shaped flex spline 80 as a flexible external gear having a portion 81 and disposed inside the circular spline 20. The configuration is the same as that of the type wave gear device 10.

The flex spline 80 has a boss portion 82 as a fixing portion for fixing to an external member (not shown), and a connection portion 83 that connects the external tooth portion 81 and the boss portion 82.

[0028] As shown in Fig. 4, the connecting portion 83 of the flex spline 80 has a cross-sectional shape when cut along a plane passing through the rotation shaft 80a of the flex spline 80 (see Fig. 3). Also, the boss 82 side force has a shape in which the thickness gradually decreases toward the center. In addition, in the connection portion 83, two opposing outlines 83a and 83b on the cross-sectional shape when cut along a plane passing through the rotating shaft 8Oa are substantially circular arcs. Further, a part of the connecting portion 83 projects to the surface 82b side of the boss portion 82 opposite to the outer tooth portion 81 side with respect to the surface 82a of the boss portion 82 on the outer tooth portion 81 side.

[0029] It should be noted that the outline 83a is formed by an arc 84 as a first arc of a radius R1 and a center position Ol that are continuous with the external tooth portion 81 and the boss portion 82. The outer line 83b includes an arc 85 as a second arc at the radius R2 and the center position 02 connected to the outer tooth portion 81, and a second arc portion at the radius R3 and the center position 03 connected to the arc 85 and the boss portion 82. 86 and is formed by. Here, the circular arc 84 and the circular arc 85 form the thinnest portion 87 at the approximate center where the thickness is the thinnest among the cross-sectional shapes of the connecting portion 83 when cut along a plane passing through the rotating shaft 80a. In other words, the point where the straight line passing through the center position Ol of the first arc and the center position 02 of the second arc intersects the first and second arcs is located at the center of the connecting portion 83. The radius R1 is smaller than the radius R2 and the distance from the thinnest part 87 to the center position Ol is shorter than the distance from the thinnest part 87 to the center position 02. Next, the operation of the cup type wave gear device 60 will be described.

[0031] For example, in the cup-type wave gear device 60, the circular spline 20, the boss 82 of the flex spline 80, and the cam 41 of the wave generator 40 are fixed to the casing, output shaft, and input shaft of the industrial robot, respectively. In this state, when rotational motion is input from the input shaft to the cam 41 of the wave generator 40, the rotational motion input to the cam 41 of the wave generator 40 is decelerated internally and from the boss portion 82 of the flex spline 80. Output to the output shaft.

[0032] When the cup-type wave gear device 60 internally decelerates the rotational motion input to the cam 41 of the wave generator 40 and outputs it from the boss portion 82 of the flex spline 80, the cup sprocket 20 Torque is transmitted to 80, but the cross-sectional shape of the connection part 83 of the flex spline 80 when cut along a plane passing through the rotary shaft 80a of the flex spline 80 is substantially from the external tooth part 81 side and the boss part 82 side. Since the thickness is gradually reduced toward the center, it is possible to suppress the concentration of stress on a part of the flex spline 80 due to the torque transmitted from the circular spline 20 to the flex spline 80 as compared with the related art.

[0033] As described above, the cup-type wave gear device 60 has conventionally suppressed the concentration of stress on a part of the flex spline 80 due to the torque transmitted from the circular spline 20 to the flex spline 80. Therefore, when the size and weight are the same as in the past, larger torque can be transmitted, and when the size of the torque that can be transmitted is the same as in the past, the size and weight can be reduced. This can be reduced compared to the prior art.

[0034] Further, in the cup-type wave gear device 60, the thinnest portion 87 is formed by the arc 84 and the arc 85, and the shape of the thinnest portion 87 is simple, so that the flex spline 80 can be easily processed. Can be Note that the thinnest portion 87 may have a more complicated shape.

In the cup-type wave gear device 60, the outline 83a is a complete arc. However, if the outlines 83a and 83b are substantially arcs as a whole, at least the outline 83a and the outline 83b are at least. One does not have to be a complete arc. For example, the cup-type wave gear device 60 may have a straight portion at least part of the outlines 83a and 83b as long as the outlines 83a and 83b are substantially arcs as a whole.

Industrial applicability

[0036] As described above, the wave gear device according to the present invention can transmit a torque larger than the conventional one. It has the best effect and is useful as a wave gear device used in the industrial robot field, semiconductor field, medical equipment field, navigation, etc.

Claims

The scope of the claims

[1] An annular internal gear formed with internal teeth and an external tooth portion formed with external teeth partially meshed with the internal teeth, and arranged inside the internal gear. A flexible external gear, and a wave generator that is disposed inside the external gear and rotates with respect to the internal gear while the external gear is swallowed.

The external gear has a fixing part for fixing to an external member, and a connection part for connecting the external tooth part and the fixing part,

The connection portion has a shape in which a cross-sectional shape when cut along a plane passing through the rotation axis of the external gear is gradually reduced in thickness from the external tooth portion side and the fixed portion side toward substantially the center. 2. A wave gear device, wherein two opposing outlines on a cross-sectional shape are substantially circular arcs.

[2] At least a part of one of the two outlines is a first arc,

At least a part of the other of the two outlines is a second arc having a different radius and center position from the first arc,

2. The wave gear device according to claim 1, wherein the first arc and the second arc form a thinnest portion at a substantially central portion having the smallest thickness among the cross-sectional shapes.

[3] At least a part of one of the two outlines is a first arc,

At least a part of the other of the two outlines is a second arc,

The first arc and the second arc are defined by a center position of the first arc and a center position of the second arc that are smaller than a radius of the first arc and a radius of the second arc. The straight line force that passes through the first circular arc and the second circular arc at a substantially center between the external tooth portion side and the fixed portion side in the cross-sectional shape of the connection portion. Wave gear device.